Integrated Application of Selenium and Silicon Enhances Growth and Anatomical Structure, Antioxidant Defense System and Yield of Wheat Grown in Salt-Stressed Soil

Selenium (Se) and silicon (Si) are considered advantageous elements to induce plants' tolerance to various environmental stresses. Wheat yield is negatively affected by salinity stress, especially in dry and semi-dry areas. Therefore, the objective of the current study was to investigate the effects of Se, Si and their combinations (0 as control, Se-15, Se-30, Si-15, Si-30, Se-15 + Si-15, and Se-30 + Si-30 mM) in alleviating the deleterious effects of salinity stress (7.61 dS m(-1), real field conditions) on anatomical characteristics as well as the physio-biochemical and productivity parameters of wheat plants. The selenium and silicon treatments and their combinations caused significant amelioration in growth, anatomical and physiological attributes, and grain yields of salinity-stressed wheat in comparison with the untreated plants (control treatment). The integrated application of Se-30 + Si-30 significantly increased plant growth (i.e., plant height 28.24%, number of tillers m(-2) 76.81%, fresh weight plant(-1) 80.66%, and dry weight plant(-1) 79.65%), Fv/Fm (44.78%), performance index (PI; 60.45%), membrane stability index (MSI; 36.39%), relative water content (RWC; 29.39%), total soluble sugars (TSS; 53.38%), proline (33.74%), enzymatic antioxidants (i.e., CAT activity by 14.45%, GR activity by 67.5%, SOD activity by 35.37% and APX activity by 39.25%) and non-enzymatic antioxidants (i.e., GSH content by 117.5%, AsA content by 52.32%), yield and its components (i.e., number of spikelets spike(-1) 29.55%, 1000-grain weight 48.73% and grain yield ha(-1) 26.44%). The anatomical traits of stem and leaves were improved in wheat plants treated with Se-30 + Si-30. These changes resulting from the exogenous applications of Se, Si or their combinations, in turn, make these elements prospective in helping wheat plants to acclimate successfully to saline soil.